Praying for windless days and calm seas

In Sweden, Vindkompaniet's learn-as-you-go approach to the intricacies of installing wind turbines offshore is moving right along -- with plenty of obstacles to provide lesson material. Installation of five Wind World 500 kW turbines is now progressing in the Näsudden pilot project near the island of Gotland, with a forecast for all machines to be up and running by the end of the year (Windpower Monthly, August 1997).

Logistics must be planned in excruciating detail, the company has found. One tool or a few essential bolts left behind in the harbour means a two hour delay work delay. The chain of transport has also been complex and weather sensitive. The turbines were shipped from Denmark to Klintehamn, reloaded to barges and towed to the small Burgsvik harbour. From here, they were transferred to an automobile ferry and sailed to the installation platform in the bay.

The platform must be towed to the monopile building sites. With four large steel pipes standing on the bottom of the sea, the platform is as steady as land, but can only be moved when the sea is calm -- a seldom circumstance in these relatively shallow waters.

Most of the work has been done during the night, when the winds and waves are still. In the summer, the sea was flat as a mirror for several weeks, but work was prohibited by the authorities who were concerned it would disturb seals in the area, an expensive delay. So far, these near sighted mammals have not been scared away, seeming to enjoy the show illuminated by bright spotlights in their waters.

Vindkompaniet hopes to use lessons learned from this project to find a rational method to install a 35 MW offshore wind farm in Näsudden as well as several other offshore projects in coming years.